Figure 3 from Coevolution of Atypical BRAF and KRAS Mutations in Colorectal Tumorigenesis

Classes of BRAF mutation exhibit distinct clinicopathologic and molecular characteristics. A, Subdivision of the large bowel into the proximal and distal colorectum. Proportions of colorectal cancers in each location are shown by BRAF mutation class. B, CMS classifications of BRAF-mutant colorectal cancers by mutation class. The differences between class 2 or 3 versus class 1 (V600E) were highly significant (P < 0.001). No significant difference was observed between classes 2 and 3 (P = 0.270). C and D, Sanger sequencing chromatograms highlighting the spatial co-occurrence of BRAF and additional Ras pathway mutations in two colorectal cancers. Two regions of each cancer were microdissected, DNA was extracted, and relevant exons were PCR-amplified prior to Sanger sequencing. Illustrative results are shown. The co-occurrence of BRAFG466V and NRASG12D can be observed in tumor 1 (C), and of BRAFD594G and KRASL19F in tumor 2 (D). This analysis does not exclude fine-scale spatial mixing of distinct subclones but is consistent with the two mutations tested being present in the same tumor cells. (Created with BioRender.com.)